With the very same argumentation you could declare Herodotus' Egypt as an unreal country.
Egypt is not 11340 years old, as Herodotus stated. The Nile is not as long as Herodotus stated.
The Egyptian king list of Herodotus is partially screwed up. Etc. etc.
But Egypt is real. There are understandable reasons why Herodotus got it wrong unintentionally.
And the same applies to Plato and Atlantis.
Plato's notion of 9000 years is not just any fabled number of years, it fits into Plato's view of cyclical history and the alleged age of Egypt. It is not meant to be fiction, phantasy, an invention, unreal. Modern researchers have the task to interprete these 9000 years to modern chronologies, like the 11340 years of Herodotus (they correspond to approx. 3000 BC).
Atlantis searchers who do not consider the context are searching on a wrong way.
Atlantis skeptics who deny Atlantis not considering the context are denying in a wrong way.
Insisting on the Atlantic Ocean 9600 BC is not scientific.
It is scientific to understand why Plato and the Egyptians screwed up this or that.
And with this understanding (not without it!) you are enabled to search for the real Atlantis.
You cannot just "change" and "bend" anything as you like.
You must have an understanding why something is distorted by tradition.
This, then, is not a "rationalization of Atlantis into existance", this is the real Atlantis.
Not a fabled country, but a most likely disappointingly unimportant culture and city, such as Troy, e.g.
As the real Egypt is related to the Egypt described by Herodotus.
Maybe you should try to find Egypt on a map? It is there!
Although some things changed compared to Herodotus :-)
There is no scientific foundation involved in support of Plato's story of Atlantis.
While Egypt does exist, Herodotus' understanding of Egypt does not. The difference between the two does not make Herodotus' understanding equal to the real thing.
The whole story was meant to be an allegorical tale. Outside of mythical origins Egypt didn't have an existance prior to c.3100 BC. So any alleged age for Egypt prior to this is irrelevant.
It is the story that we have though. And yet, in all of Egypt there is no mention of anything that could be remotely understood as Atlantis. So the Egyptians didn't screw up anything. If anyone did, it was Plato. As to changing things as you like, that's exactly what you're doing. The story, as a place, doesn't exist prior to Plato and exists nowhere in Ancient Egyptian myths or legends. Plato is its start and finish.